Shiga toxin-producing E. coli (STEC) Infections

Last Reviewed: August 2017

What is STEC?

E. coli are a diverse group of bacteria that normally live in the intestines of humans and animals. Although most strains of these bacteria are harmless, some produce toxins that can make you sick and cause diarrhea (loose stool/poop) such as Shiga toxin-producing E. coli (STEC). E. coli O157:H7 is the most common strain of STEC, but there are many other strains of STEC as well.

Who gets STEC infections?

Anyone can get STEC infection. Young children and the elderly are more susceptible to develop serious infection, but healthy older children and young adults can also become seriously ill.

How does STEC spread?

People become infected with STEC when they eat any product contaminated with the bacteria. The bacteria live in the intestines of healthy cattle, and contamination of their meat may occur during the slaughtering process. Infection most typically occurs by eating contaminated food, particularly raw or undercooked meat. Infection can also occur after eating of any product contaminated with STEC, including lettuce, alfalfa sprouts, salami, and raw (unpasteurized) milk, juice, or cider. Infected people can spread E. coli to other people if they do not wash their hands after using the toilet.

What are the symptoms of STEC infections and when do they appear?

Symptoms of STEC infections can vary, but most often include severe diarrhea (loose stool/poop), stomach cramps, and vomiting. Diarrhea is often bloody and usually little or no fever is present. Symptoms typically appear 3-4 days after eating (or having direct contact with) a contaminated product, but can range from 1-10 days.

How are STEC infections diagnosed?

STEC infections are most often diagnosed through laboratory testing of stool (poop) specimens.

What is the treatment for STEC infections?

There is no specific treatment for STEC infections. Since diarrhea can cause dehydration (loss of water in the body causing weakness or dizziness), drinking plenty of fluids to stay hydrated is important. Antibiotics should not be used for the treatment of STEC infection since there is no evidence that antibiotics are helpful with these infections and may increase the risk of developing hemolytic uremic syndrome (HUS).

What can be done to help prevent STEC infections?

  1. Always handle raw meat, especially ground beef, according to these recommendations:
    • Wrap fresh meats in plastic bags at the market to prevent blood and juices from dripping on to other foods. Refrigerate promptly; do not store at room temperature.
    • Never place cooked food on an unwashed plate that previously held raw beef, poultry, pork, fish, or seafood.
    • Cutting boards and counters used for beef, poultry, pork, fish, or seafood preparation should be washed immediately after use to prevent cross contamination with other foods.
    • Avoid eating raw or undercooked meats. While the juice color will usually change from red to gray when the meat is fully cooked, it is not a reliable test to assure it is safe to eat.
    • Always check the temperature of cooked foods with a meat thermometer. Foods that reach the temperatures listed below (or higher) are considered fully cooked.
    • Food Temperature
      Chicken 165° F
      Hamburger 160° F
      Pork 150° F
      Hot dogs 140° F
      Leftovers 165° F
      Eggs 145° F
      Other foods 140° F
  2. Avoid drinking raw (unpasteurized) milk, juices, and cider.
  3. Wash fruits and vegetables thoroughly, especially those that will be eaten raw.
  4. Wash hands with soap and water before and after food preparation, as well as, before eating.
  5. Wash hands with soap and water after using the toilet, changing diapers, and after any animal contact (at home, farms, petting zoos, etc.).
  6. Do not drink water from untreated sources (including roadside springs) and avoid swallowing water from recreational water sources (including lakes, streams, and swimming pools).